Houston’s air quality has long suffered. Much of the city’s air pollution problem is due to its proximity to the ship channel industries which compose the largest petrochemical complex in the nation- comprising over 60 percent of the country’s petrochemical industry. In 2000, an analysis of the city’s air revealed that industry had been consistently underreporting its emissions of volatile organic compounds (VOCs)- precursors to ozone- by a factor of 3 to 10 times. Ground-level ozone, also known as smog, is Houston’s most prevalent air pollution problem. In fact, Houston rivals Los Angeles as the country’s smoggiest city. There is, however, a major difference in the sources of the cities’ air pollution. The majority of Los Angeles’ smog creating emissions comes from its vehicles, while only about a quarter of our smog forming pollution emanates from automobile tailpipes. The industries along the ship channel contribute overwhelmingly to Houston’s air pollution problem.